we sent this rover to discover habitable environments on mars, and we did discover one already, early in the mission. we found that we landed right on an ancient stream bed, where water was once flowing kind of up to your kneecaps. >> reporter: 100% sure it was water? the kind of water we have on earth? >> i wouldn't say 100%, but it's the most likely thing. you know, we know that there's water on mars frozen in ice today. and in the past, we think the conditions were more that liquid water could have been staple. >> reporter: "curiosity" is embarking on a new task on mars, after practicing on earth-- drilling into martian rocks for the first time. using remotely controlled tools built into the rover, nasa will bore into rocks to find out what they're made of, and if they contain clues to life on the red planet. >> this whole arm, in a series of tai chi moves, moves around and sieves that powder, and then dumps it into some inlets that are on the top of the rover deck, so that instruments which are inside the rover can analyze it for its chemistry. >> reporter: the mars mission wouldn